A tearful Steve Ballmer has admitted he was a big part of the problem at Microsoft – and that the company needs to rethink its management structure to succeed in the future.

"At the end of the day, we need to break a pattern. Face it: I'm a pattern," company CEO Ballmer toldThe Wall Street Journal with apparent tears in his eyes.

"Maybe I'm an emblem of an old era, and I have to move on. As much as I love everything about what I'm doing the best way for Microsoft to enter a new era is a new leader who will accelerate change."

Ballmer, due to retire by August 2014, said he had been trying to make Microsoft change its business strategy to focus on the cloud and mobile, rather than its desktop roots, since October last year. But the rate of change wasn't fast enough and board members were growing frustrated.

He singled out John Thompson, Symantec's former CEO, as a particular critic. Board member Thompson told the WSJ that he didn't force Ballmer to step down, but was "pushing him damn hard to go faster."

"Hey, dude, let's get on with it," Thompson said he told Ballmer. "We're in suspended animation."

Shy and retiring Ballmer said he had a particularly driven management style that permeated the company during the 13 years of his leadership, and that was reflected in his line managers who were too focused on his old management style. "I'm big, I'm bald and I'm loud," he said.

He cited one problem as Microsoft's much-hated "stack ranking" employee-rating system, whereby staff are scored on a scale of one to five based on their performance. Crucially, a set number of workers must receive a "poor" ranking irrespective of their success. The system was axed earlier this week and Ballmer acknowledged that it had led to corporate politicking and self-promotion.

Ballmer said he decided to step down in May, during a trip to London, when he realized that Microsoft would probably move faster without him at the helm. On the flight back to the US he told Microsoft's general counsel Brad Smith that it "might be the time for me to go," and informed Thompson a day later.

The board wasn't surprised or shocked, he said, but resolved to get on with the job of finding a successor. Ballmer's old friend and poker buddy Bill Gates said he agreed with the decision if it was in the best interests of the company.

The next day he told his family after his son's graduation ceremony, where the students sang a Coldplay song with the lyrics "It's such a shame for us to part; nobody said it was easy; no one ever said it would be this hard." The news moved the entire family to tears, Ballmer reports.

Ballmer, Gates and Thompson met at his office on August 21 and held a conference call to announce his resignation. The meeting took less than an hour, he recounts, and the search was started for his successor.

Ballmer said he's not selling his huge stake in Microsoft, and would like to remain on the board. In the meantime he's looking at his options. He's not interested in running another big company, but said there have been some interesting offers, including coaching his son's school basketball team. He insisted he was no lame duck.

"Charge! Charge! Charge!" he shouted at the interviewer. "I'm not going to wimp away from anything!" ®